Strand tensioning and metering apparatus



July 3, 1962 N. E. KLEIN STRAND TENSIONING AND METERING APPARATUS 3Sheets-Sheet 1 Filed May 23, 1956 v A m m w.

NORMAN E KLEIN BY MkflZZM ATTORNEY July 3, 1962 N. E. KLEIN STRANDTENSIONING AND METERING APPARATUS 3 Sheets-Sheet 2 Filed May 23, 1956JNVENTOR.

. NORMAN E. KLEIN ATTo RNEY July 3, 1962 N. E. KLEIN STRAND TENSIONINGAND METERING APPARATUS 3 Sheet 3 Filed May 25, 1956 A Y TA I;

VENTOR,

NORMAN KLEIN 572 b- BY M ORNEY United States Patent Ofi" 3,041,815.Patented July 3, 1962 3,641,815 STRAND TENSIGNING AND METERING ArPAnArUsNorman E. Klein, Pendleton, S.C., assignor to Bearing Millikan ResearchCorporation, Pendleton, S.C., a corporation of Delaware Filed May 23,1956, Ser. No. 586,86 44 Claims. (Cl. 5758.3)

This invention relates to ply action twisters, and more particularly tonew and improved equalizer strand tension control arrangements for suchapparatus.

By way of a brief explanation of some of the terminology employed inthis application, it may be noted that with the introduction of feedback control in the textile trade a conflict in terminology has arisen.In many instances tension devices in the textile trade are spoken of astension controls when they actually do not more than add a fixed amountof tension or pull to a strand or in other cases provide a constantmultiplier which merely amplifies the original tension value includingall variations. To differentiate between devices or elements that havecontrol and those that do not and still speak within the parlance oftextile terminology the words dynamic and static have been respectivelyadded to clarify this interpretation.

In copending applications of Norman E. Klein and Edward J. Wright,Serial Number 512,552, now US. Patent No. 2,914,903, and Klein, SerialNumber 516,- 391, now US. Patent No. 2,961,82A, there are disclosed plyaction twister arrangements for ply twisting two strands of yarn into atwo ply yarn or cord, which employ a capstan array comprising a pair ofcanted capstans connected together for synchronous rotation about theirrespective axes through the medium of an idler gear which is alsorotatively mounted about a central axis. A separate strand of yarn isfed to each of these two capstans, each yarn from a separate source ofsupply, with one of the strands being driven in ballooned relation aboutthe source of supply for the other of the strands. The ballooned yarnstrand serves to impart rotation to the capstan unit, and by bringingthe two strands together at a Y-ply point beyond the two canted capstansand along the axis of rotation of the idler gear a highly advantageousplying action will take place, thereby forming a two ply cord which iscontinually pulled away from the ply point by a suitable means. Thesecapstans serve very effectively to meter the yarn fiow of the twostrands each at the same rate to the plying point and under widevariations of tension. It is, however, desirable that the tension in thetwo strands being plied be approximately equalized, particularly in thecase of resilient or elastic material such as nylon, in order to avoidthe formation of a yarn or cord which has unbalanced twist or corkscrewconfiguration, wherein tensile strength is impaired.

In the previous devices there is provision for both static initialadjustment and dynamic tension control of the ballooned strand; however,there is only provision for static tension adjustment of the innerstrand, with no dynamic operational tension control to alleviate anyoperational tension variations, such as may occur in the inner strandfor various reasons. While apparatus according to these applicationsfunction well for most purposes, even with moderate tensiondifferentials existing between the two strands as they feed into the twometering capstans (due particularly to the yarn metering controlfunction of the two metering capstans), tension differentials maysometimes occur which are suificiently large as to cause strand slippageon one or both of the capstans, with consequent uneven feeding of-thestrands to the ply point during such periods, thereby causingundesirable plied cord variations and configurations. Not only may thesedifferential tensions occur during normal running of the plyingapparatus, but such particularly may occur during startirg and stoppingof the apparatus due to the ballooning strand having a dynamic feed backtension control as well as a static control, while the inner strand hasonly a static control for the tension thereof.

It is, therefore, an object of this invention to provide an improved plyaction capstan array having an inner strand dynamic feed-back tensioncontrol.

A further object is to provide an improved metering capstan array havingan inner strand constant tension feedback control.

Still a further object of this invention is to provide an improved plyaction metering capstan array having an inner strand dynamic feedbackcontrol which is speed responsive.

Another object of the invention is to provide an improved ply actionapparatus having a feed back tension control for each of the outerballooned strand and the inner strand.

A further object is to provide an improved ply action apparatus having adynamic feed back control for each of the outer ballooning strand andthe inner strand, both tension controls being responsive to the rate ofrotation of the ballooned strand about the ply axis, wherebydifferential strand tension will be held to a minimum during normalrunning operation and during starting and stopping of the apparatus.

A still further object of the invention is to provide an improved plyaction apparatus of the type wherein a false twist is inserted in thestrands during a portion of the pre-plying operation and is taken out ofthe strand during plying thereof, which is so arranged as to permit theinner strand to be maintained under low tension at the point of twistinsertion while being maintained under a torque-controlled highertension as it proceeds thereafter to the ply point.

Still a further object of the invention is to provide an improved strandtension device particularly adaptable to ply action apparatus andemploying a torque-brakecontrolled rotatable yarn engaging member and aseparately rotatable yarn guide for maintaining tension on e a strand,the member and guide being each rotatable about a common axis.

A still further object is to provide an improved strand tension device,particularly adapted to ply action apparatus, in which two members arerotatable, one by direct action of one of two strands being plied andthe other by intercoupling the two members through the second strand,with the second member having a controlled braking torque exertedthereon to thereby control the tension of the second strand.

Still other objects and many attendant advantages will become apparentfrom the following detailed description of the preferred and severalother embodiments of various aspects of the invention, taken inconjunction with the accompanying drawings, wherein:

FIGURE 1 illustrates schematically the general arrangement of a plyaction apparatus incorporating the invention;

FIGURE 2 is a view in partial section of a metering and tensioningcapstan arrangement according to the in vention and as illustratedgenerally in FIGURE 1;

FIGURE 3 is a fragmentary plan view of the arrangement of FIGURE 1,further illustrating the capstan arrangement;

FIGURE 4 is a plan View of the face magnet of FIG- URE 3;

FIGURE 5 is a partial diametral section view of a modified capstanarrangement according to the invention;

FIGURES 6 and 7 are section views taken on lines 66 and 77 of FIGUREFIGURE 8 is a perspective view of one of the gears of the embodiment ofFIGURE 5;

FIGURE 9 is a fragmentary sectional view of a further capstan brakemodification;

FIGURE 10 is a partial sectional view of still another modificationaccording to one aspect of the invention;

FIGURES 11 and 12 are perspective and diametral section views of the capend portion of the preferred embodiment of the wrap-around tensioningcapstan;

FIGURE 13 is a perspective view of the outer end portion of a modifiedwrap-around tensioning capstan;

FIGURE 14 is a section view taken along line 14-14 of FIGURE 13; and

FIGURES l5 and 16 are plan and fragmentary side elevation views of amodified embodiment according to another aspect.

Briefly a preferred embodiment of the invention takes the form of a pairof symmetrically arranged capstans having individual axis of rotationcanted with respect to each other and with respect to a major axis ofrotation common to both capstans, the capstans being arranged for meshedengagement with a common idler gear which is in turn rotatably mountedfor free rotation about said major axis. Strands being plied are fed toa ply point in substantially synchronously metered relation by passingthe strands in tractive engagement each with a separate one of the twometering capstans of an equalizer or metering capstan array. The outerballooning strand first passes through an additive pre-tensioningdevice, then through a hollow spindle and in variable wraparoundengagement with a wrap-around step dynamic balloon shape and tensioncontrol, after which it passes in a balloon about the supply package forthe second or inner strand, and thence through a coupling or drivingguide on the equalizer or meter-ing capstan array and in tractiveengagement with one of the two metering capstans, from which it passesto the inverted Y-ply point. The inner strand proceeds from its supplypackage upwardly through a pre-tensioning arrangement (preferably of thepad or pinch-tensioning type) then through an axial bore in a rotatablewrap-around tension capstan (which functions on a torque controlprinciple) concentrio with the plying axis, passing thence about and invariable wrap-around engagement with the peripheral surface of theWrap-around capstan, then in tractive engagement with the other of thetwo metering capstans, from which it then progresses to the invertedY-ply point. The rotatable wrap-around tension capstan is braked bysuitable means (which in the preferred embodiment operates on a magneticeddy current principle), causing the tension in the inner strand as itpasses to the metering capstan to be controlled by the degree ofwrap-around about the peripheral surface of said Wrap-around capstan;the degree of Wrap-around being in turn a function of the braking torqueexerted on the wrap-around capstan by the magnetic brake and thedifierence in the input tension of the inner strand as it passes theretoand the required inner strand output tension to yield a torque on thecapstan of equal and opposite magnitude to the brake torque therein. Inthis preferred embodiment wherein a magnetic eddy current brake isutilized, the braking action (and thus the strand output tension) isdependent upon the speed of rotation of the capstan array, and thetension on the inner strandis dynamically controlled similarly to theouter ballooned strand, matching the action of the Wrap-around stepdynamic tension and balloon shape control since this outer strand isgoverned by a similar speed-tension response characteristic. The netresult is an improved ply action apparatus including substantiallybalanced dynamic tensioning means for both the inner and outer strands,with resultant minimizing of differential tensions in the two strandsprior to their being plied. A further advantage resides in the fact thatthe inner strand tension may be maintained at a low value at the pointof twist insertion (with resulant minimizing of broken ends in the innerstrand) while controllably regulating the tension between this twistpoint and the ply point at such higher tension value as may be desiredfor matching the tension of the outer strand.

In addition to the preferred embodiment as briefly described above thereare also disclosed several alternative embodiments and modifications ofthe invention, each of which will be described in detail in thefollowing paragraphs.

Referring to FIGURE 1, a strand of a yarn A from an external source,such as supply package 11, is fed through adjustable tensioning assembly13, thence axially through the center of hollow rotatably driven spindleshaft 15, through a radial opening in the shaft 15, then in wrap-aroundrelation about wrap-around step tension balloon shape control 17 (ofconventional construction), which forms a dynamic strand-tensionresponsive negative feed-back tension and balloon shape control device,such as shown for instance in the Klein and Wright application SerialNo. 512,552, filed June 1, 1955, and in a semi-loop or balloon about theexterior surface of cylinr cal housing 19, and thence through a pigtailcoupling guide 24: and in tractive Wrap-around relation about onecapstan 73a in a symmetrical capstan array, generally designated 40, toa ply point with another strand B. Strand B is fed from an internalsource of yarn disposed within the thus formed balloon (for example,from a yarn package 21 mounted within the cylindrical housing 19, whichpackage and housing are restrained against rotation as by an off centerWeight 22, as shown, or by magnetic action, etc.), through adjustablepre-tensioning assembly 23 (in the instant example a plurality ofdisctype tensioners 23a mounted in spaced apart relation on ashock-mounted plate 23b) and thence about a guide roller 24 and throughan axial bore in an axially disposed torque wrap-around capstan 26 inthe capstan array 49, thence in sliding frictional wrap-around relationabout the end of the capstan 26, then in tractive wrap-around relationabout the other rotatable capstan 79b of the array 40, and thereuponproceeding to the ply point of the two strands.

The plied yarn or cord AB is fed from the ply point by a constant speeddriven feed roll arrangement 25, and thence on to a take-up bobbin 27driven in any suitable manner, as by surface contact roll 29. Thespindle shaft 1'5, feed roll arrangement 25 and surface drive roll 29may be synchronously driven from either common or independent sources ofpower, as described and illustrated in the above mentioned co-pendingapplication of Klein and Wright, and is, therefore, not shown herein.

Capstan array 49 is mounted on a supporting bracket 32 suitably securedat its base end 34 as by screws 35 to the upper end of cylindricalhousing 19, and having formed at its upper end an adjustable internallythreaded split clamping sleeve 36. Capstan array 49 comprises a housing42, the lower end 44 of which is threaded for complementary engagementwith threaded sleeve 36. The housing 42 is securely held in threadedengagement with the clamping sleeve 36 as by a bolt 38 extending througha pair of ears 39 formed on the sleeve 36, as more clearly seen inFIGURES 2 and 3.

Press fit into shouldered recesses in housing 42 are two low-frictionbearings 46 and 48 (i.e. ball bearings or other suitable construction asmay be desired) which support within the inner race thereof for freerotation therein a rotor shaft 56, the axis of rotation of which isaligned with the axis of rotation of spindle shaft 15 as illustrated inthe instant embodiment. The lower end recess in the housing 42 isinternally threaded below the lower end of bearing 48, as indicated bythe numeral 50, for the reception of a complementary threadedferromagnetic field adjustment ring 52. Field adjustment ring 52 has aplurality of radial air cooling holes 54 formed therein. The purpose ofthis ring 52 will be described in more detail as the desc.ptionproceeds. The lower end of rotor shaft 56 is threaded and has a securingnut 58 secured thereto for preventing upward axial displace mentthereof. If desired, a set screw 59 may be employed to retain the nut 58in secured relation on rotor shaft 56.

The upper end of rotor shaft 56 is enlarged to form a head 60 having apair of opposed upwardly and inwardly inclined faces 61a and 61b,adjacent each of which is supported one of the strand metering capstans70a and 70b. Each of capstans 70a and 70b is arranged for rotation aboutan axis perpendicular to the plane of its respective adjacent face 61aand 61b, and to this end stub shafts 62 are threadedly secured in arespective tapped bore in each of the faces 61a and 61b. Intermediatethe ends of each of stub shafts 62 is a standoff collar 63 against oneend of which is secured the inner race of a low friction bearing 64 heldon the end of the stub shaft by a lock nut 66 threadedly secured on thefree end of the shaft. The outer race of each of the bearings 64 ispress fitted into the bore of respective capstans 70a and 70b, wherebyeach capstan is thus adapted for free rotation about its respective stubshaft 62. In the illustrated embodiment, capstans 70a and 70b have asingle sharp-angled groove formed therein as indicated at 72, in orderto provide maximum tractive action between the yarn strands A, B andtheir respective capstans 70a and 70b; however, this tractionarrangement for the capstans may be modified as may be desired to fitthe needs of any particular instance of use. Capstans 70a and 70b arecoupled together for synchronous rotation about their respective cantedaxes through the medium of a rotatable idler face gear 80 in meshedrelation with beveled gears 76 formed integral with, as illustrated, orconnected to the adjacent end of each of the capstans 70a and 70b. Tothis end face gear 80 has a central shouldered recess which is pressfitted over the outer race of a bearing 82, the retention of which isassisted by a snap ring 84 releasably fitted Within a shallow groove inthe inner peripheral wall of the recess.

Rotor shaft 56 has an axial bore running therethrough, in the upper endof which is formed a counterbored shouldered recess 92 for press fittedreception of the outer race of a low friction ball bearing 94. The nut58 at the lower end of rotor 56 has a skirt 96 formed thereon, the lowerend of which skirt has a shouldered recess formed therein for pressfitted reception of the outer race of another low friction ball bearing98. Mounted for rotation in bearings 94 and 98, by press fit in theinner race of each of these bearings, is an inner rotatable torque shaft100 having a central bore 102 formed therein. The upper end of torqueshaft 100 has formed thereon or suitably secured thereon (as by a pressfit as illustrated), for rotation therewith, a yarn guiding and torquetransmitting wrap-around capstan 104 having a spiral end groove 106formed therein for the guiding of strand B, as will become more readilyapparent hereinafter. In the preferred example as illustrated in FIGURES2 and 3, as well as FIGURES l1 and 12, the groove 106 takes the form ofa single spiral groove and connects with the' bore 102 in torque shaft100 through an enlarged 01f center aperture 105. The aperture 105 is sooffset from the axis of axial capstan 26, including torque shaft 100 andcapstan 104, as to form a yarn engaging surface such that the strand Bpassing therethrough will be substantially coaxial with the torque shaft100. It will be apparent that this arrangement of the aperture 105 willnot only serve to maintain the strand B in a dynamically balancedposition as it proceeds through the torque shaft 100 and the centeraperture 105 in the cap 104, but will also accomplish the highlyadvantageous function of substantially reducing, if not completelyeliminating, strand contact with the inner surface of tube shaft as itpasses therethrough. Dynamic balancing of end cap 104 may readily beaccomplished in any suitable or desired manner, as by the forming of theoff center aperture of suflicient size as to offset formation of groove106, or by addition of balancing weight or the like, as may be desired.

The lower end of torque shaft 100 has secured thereto, as by a set screw110, a metallic disc 108 which is preferably made of low magneticreluctance material such as aluminum, etc. Supported in concentricrelation beneath metallic disc 108 is a face magnet 112 having aplurality of circumferentially spaced, alternately north, south poles114. Face magnet 112 may be sup ported in any suitable manner, as forexample, by being secured through the medium of securing screws 118 to asupport flange 116 which forms a part of support bracket 32.Conveniently, support flange 116 may also serve to support guide roll 24for axial guiding of the strand to torque shaft 100.

In operation, strand A passes through spindle shaft 15, and then invariable surface contact with wrap around step 17, after which it passesin balloon form through guide 20 and in tractive engagement with capstan70a, from which it proceeds to the ply point. The tension in this strandis preadjusted by adjustment of the adjustable static pre-tensioningarray 13, in order to provide the desired balloon size range for thestrand as it passes in balloon shape about the housing 19. The tensionin the strand A as it proceeds through the balloon portion of its pathis self-maintained by the variable wrap-around of the strand onwrap-around step 17 by interacting negative feed-back response betweenthe step 17 and the balloon strand. As is well known in the art, thevariation of wrap-around of the ballooning strand on wrap-around step 17is a function of strand input and balloon tension, wind resistance toballoon movement and rate of rotation of the balloon, among otherfactors, and varies in such a manner by negative feed-back response asto tend to keep the tension constant in the strand A. Thus, an increaseor decrease in balloon tension causes a smaller or larger wrap angle onthe step 17, and this effects a negative feed-back control responsebetween the strand and the step 17 in that a decreased or increasedtension multiple is thereby applied to the strand by the step 17 as afunction of the change in wrap angle, and this in turn tends to restorethe balloon tension and size in a negative direction toward the desiredvalue. This system of yarn tension control for strand A is quiteadvantageous as is well known in the art and serves to maintain asubstantially constant tension in strand A during normal operation atone balloon velocity. However, as is also well known in the art, sincethe control exerted by this wrap-around step system is a function ofballoon rotational velocity, variations of balloon velocity such as mayoccur for example during starting and stopping of the apparatus causecorresponding variations in the balloon tension of strand A. It is,therefore, extremely desirable that any dynamic tension control for theinner strand B maintain a tension control which is a function of therate of rotation of the balloon A in as closely a similar manner to thespeed responsive tension control exerted by the wrap-around step 17 asis possible.

To this end there is provided as a complementary adjunct to thewrap-around step tension control for strand A the axial wrap-aroundtorque capstan 26 (including torque shaft 100, torque transmittingwrap-around cap 104, and disc 108, as described above), which serves inconjunction with face magnet 112 as a further dynamicstrand-tension-responsive negative feed-back tension control device tomaintain a normally constant output tension on the strand B as itproceeds from the cap 104 to the metering capstan 70b. The torquecapstan assembly 26 functions in a negative feed-back responsive mannerto maintain a desired tension level in the strand B closely analogous tothe function of variable wrap angle step 17 for the strand A. Thus, ifthe output tension should decrease or increase by a slight or largeramount the drag exerted on the torque capstan assembly 26 willinherently effect a negative feed-back response between the strand B andthe torque capstan assembly, which response takes the form of acorresponding increase or decrease, respectively, in wrap angle of thestrand about the cap 104, to thereby restore the strand to the desiredtension level.

As stated above, strand B proceeds from guide roller 24 axially throughaxial bore 102 in torque shaft 160 through groove 106 and cap 104, andthen in wraparound relation about the circumferential peripheral surfaceof cap 104, from which it passes through and in tractive rollingfrictional engagement with metering capstan 70b, after which it proceedsto the ply point. Upon rotation of the entire capstan array 40 throughthe action of balloon strand A as exerted on the capstan array throughits engagement with coupling guide 20 and/or metering capstan 70a, theentire capstan array 40, in cluding the disc 108, will be rotated aboutits common or major axis, and drag torque will be exerted on torquetransmitting wrap-around capstan 26 through the rotation of disc 108 inthe magnetic field between face magnet 112 and field adjustment ring 52.The rotation of this disc 108 causes eddy currents to be set up thereinproportional to the rate of cutting of the magnetic lines of force whichin turn generate a magnetic field of proportional intensity which reactswith the field from magnets 114 to oppose the rotation of the disc 108,and thus the rotation of the entire torque capstan 26. The extent ofeddy currents generated in the disc 108, and thus the extent of brakingaction exerted on the torque capstan 26 by the magnet 112 is therefore afunction of the rate of rotation of the disc 108.

Since the torque capstan 26 (including disc 108) is coupled for rotationwith the rotor 56 and capstans 76a, 70b, through the strand couplingbetween torque wraparound cap 104 and capstan 70b the rate of rotationof disc 108 will be substantially the same as the rate of rotation ofthe balloon of strand A, and thus the drag or brake torque exerted ontorque capstan 26 will be a function of the rate of rotation of theballoon of strand A. In other words, the greater the speed of rotationof the balloon of strand A, the greater will be the braking actionexerted by magnet 112 on wrap-around torque capstan 26, and vice versa.It will, therefore, be apparent that due to this braking torque, torquecapstan 26 will tend to rotate retrogressively relative to (i.e. lagbehind) the rotor shaft 56 and capstans 70a and 7tib, until a point ofequilibrium is reached wherein the ten sion in strand B is such as toexert a rotative torque on cap 104 which is equal and opposite to thetorque exerted on cap 104 through the braking action of magnet 112 anddisc 108. By initially setting the pretensioning array 23 (see FIGURE 1)such that the tension in the strand B as it passes through the axialbore 102 is below the desired operating tension of strand B as it passesinto engagement with metering capstan 7%, the additional tensionnecessary to bring the strand B up to the desired tension value will beadded by the tension multiplication action of the wrap-around torque cap104 on the strand. As is well known, the passage of a strand in runningfrictional contact with a cylindrical or other similar surface such asthat of torque wrap-around cap 104 results in a multiplication of thestrand tension as an exponential function of the extent of wrap-aroundangle. Thus, in the case of the torque wrap-around cap 104, the strand Bwill wrap about the outer periphery thereof until the tensionmultiplication factor as a result of this wrap-around is suificient toyield an output tension in the strand B as'it passes from cap 104 tometering capstan 70b which will give a torque equal and opposite to thatexerted by magnet 112 on disc 108. As stated above, the braking actionof magnet 112 on disc 108 is a function of the rate of rotation of disc108 (and thus for all practical purposes the rate of rotation of theballoon of strand A). For any one speed of rotation of disc 108 thebrake action thereon by magnet 112 is sub stantially constant, and forall practical purposes may be said to be actually constant. Thus, forany one rate of rotation, the magnet 112 will exert a constantpredetermined brake torque on disc 108 and the remaining portions oftorque capstan 26, including torque wrap around cap 104, whereby thestrand tension between torque wrap-around cap 104 and metering capstan7017 will be maintained at a substantially constant predeterminedtension value. It will be apparent that such minor or major inputtension variations as may occur in the strand B as it passes through theaxial bore 102 will result in correspondingly small or large rotationsof torque capstan 26 relative to rotor 56 and metering capstan 7 0bsufiicient to increase or decrease the strand wrap-around angle on theperiphery of torque wrap-around cap 104 and correspondingly increase ordecrease the tension multiplication factor to thereby maintain torqueequilibrium and corresponding substantially constant tension (duringnormal running operation) in strand B as it leaves cap 104.

The brake torque exerted on disc 108 of the torque capstan 26 mayreadily be varied for any particular rate of rotation of the disc 103relative to the magnet 112 by increasing or decreasing the flux densityof the magnetic field passing through disc 188. In the instantembodiment, this is facilely accomplished through the medium of axiallyadjustable field adjustment ring 52, which is threadedly secured in thelower threaded recess of housing 42. By manually rotating the housing42, including field adjustment ring 52 secured thereto, the axialposition of the housing 42 and ring 52 will be varied, and thereby thespacing between ring 52 and the pole faces 114 of magnet 112 will bevaried with corresponding inverse variation of the magnetic fielddensity in the air gap between pole faces 114 and the ferro-magncticring 52. It will readily be seen that the ring 52 serves as a lowreluctance portion of the magnetic path between each of the adjacentnorth-south poles 114, and thus the variation of the air gap between thering 52 and the poles 114 will correspondingly result in an inversevariation in the magnetic flux density in the air gap therebetween, inwhich air gap the disc 108 is positioned.

In order to prevent over-heating of the parts in the vicinity of themagnetic brake assembly, the field adjustment ring 52 has formed thereina plurality of radial openings 54 to permit the circulation of airthcrethrough in order to carry off a portion of the generated heatresulting from the eddy currents in disc 10%.

While the axial torque capstan 26 has been illustrated as an assembly ofseveral separate parts, including disc 108, torque shaft and torquewrap-around cap 104, and such assembly is the most desirable from thestandpoint of ease of construction and assembly, it will be apparentthat all or a part of this assembly might, if desired, be made as anintegral unit.

In FIGURES 5-8 there is illustrated a modified embodiment according tothe invention, which also incorporates a torque capstan assembly 226having a torque brake which is a function of the rate of rotation of theballoon of strand A. In this embodiment, a mechanical slip clutch-brakearrangement is utilized to maintain a desired brake torque betwen thetorque capstan assembly 226 and the rotor shaft 256. This arrangement issimilar in other respects to the arrangement of the first describedembodiment, and will thus be described only in the differing detailsthereof.

Referring to FIGURE 5, the rotor shm 256 is mounted in bearings 246, 248in a similar manner to the rotor shaft 56 of the previous embodiment, adhas secured thereto a retaining nut 258 having the lower ball bearingsupport for torque shaft 200 press fit into a recess in its lower end.Formed integral with nut 258, or press fit thereon (as illustrated), isa gear 262 which is engaged in meshed relation with a secoid gear 264disposed laterally thereof and :rotatably about an axis parallel to theaxis of torque shaft 200. The gear 264 has an axial tubular extension265 which is press fit within the inner race of each of two spaced apartlow friction ball bearings 268, 270 which in turn are press fit intoupper and lower shouldered recesses in a lateral extension 244 of thecapstan housing 242. Slidably mounted within an axial bore extendingthrough gear 264 and its extension 265 is an axially adjustable shaft266 which supports a third gear 274 in concentric relation with gear264, through the medium of a ball bearing 276 the inner race of which ispress fit onto the lower end of shaft 266 and the outer race of which ispress fit into a recess in the lower end of gear 274. A retaining nut278 serves to assure the retention of bearing 276 on shaft 266. Theaxial disposition of gear 274 relative to gear 264 is determined by theaxial position of shaft 266, which position may readily be varied asdesired through the medium of an adjustment nut 267 which engages thethreaded upper end of shaft 266 and rides on the upper end of gearextension tube 265. The gear 274 meshes with a gear 272 which is pressfit onto the lower end of torque shaft 200. The gear ratios of gears262, 264, on the one hand and gears 272, 274 on the other, arepreferably such that a low order differential (i.e. of the order of thatprovided by one or two teeth difference, or more if desired) existstherebetween.

The gears 264 and 274 are operatively coupled together through themedium of a plurality of friction blocks 284 of nylon or other suitablematerial. Blocks 284, as illustrated are rectangular in cross sectionand are loosely fitted within a corresponding pluraltiy of openings 280formed in symmetrical spaced apart relation in gear 264 and extendingparallel to the axis thereof. The openings 280 each have formed at theirlower end a fulcrum lip 282. In the upper face of gear 274 there isformed an annular groove or recess 288 which is radially aligned withthe plurality of openings 280, and in which the lower ends of frictionblocks 284 ride as guided by the depending separating segments 269between slot openings 280 (see FIGURES 6-8). Preferably each of thefriction blocks 284 has a boss 286 formed at its lower end which serves,together with an annular retaining lip 290 which may be formed on therim of groove 288, to prevent longitudinally upward movement of theblocks 284 out of groove 288. It will be noted that by axial adjustmentof the gear 274 through the medium of shaft 266 and adjustment nut 267the mass of the friction blocks 284 which lies below the fulcrum lip 282may be varied as desired to create a desired mass unbalance of theseblocks about the fulcrum points formed by their respective fulcrum lips282.

In operation the rotor shaft 256 will be rotated about its axis in asimilar manner to that of rotor shaft 56 of the previous embodiment asthrough the rotational action of ballooning strand A. Rotation of rotorshaft 256 causes corresponding rotation of gears 262 and 264. R- tationof gear 264 in turn tends to effect rotation of gears 272 and 274,together with torque wrap-around capstan 226, through the medium ofresulting centrifugal action of friction blocks 284 which frictionallyengage the outer peripheral surface of the annular groove 288 in gear274. The torque transmitting action between rotor shaft 256 and torquewrap-around capstan 226 is thus a function of the dilferentialcentrifugal force exerted by the plurality of blocks 234 on the groove288 of the gear 274, as well as being a function of the coefiicient offriction between the blocks 284 and the engaging surface of groove 288.The differential centrifugal force exerted by blocks 284 on theperipheral surface of groove 288 is in turn a function of the verticalposition of the friction blocks relative to their respective fulcrumpoints, and the speed of rotation of rotor shaft 256. Thus the torquetransmitted from shaft 256 to torque wrap-around capstan 226 is afunction of the speed of rotation of rotor shaft 256 and the balloon ofstrand A. It will be seen, however, that due to the small differentialratio between gears 262, 264 and gears 272, 274, for equal rates ofrotation of the rotor shaft 256 and torque wrap-around capstan 226 therewill be only a small difierential velocity between the rate of rotationof gear 264 relative to gear 274. It is, therefore, only necessary, todissipate a very small amount of power in the friction clutcharrangement between these two gears 264, 274 in order to transmit thedesired torque from rotor shaft 256 to the torque wrap-around capstan226, thus resulting in low heat lossand small consumption of power.

For any given speed of rotation of the balloon strand A (and thus therotor shaft 256) the friction blocks 284 will exert a substantiallyconstant predetermined centrifugal clutch-brake action on the gear 274to thereby exert a corresponding predetermined substantially constant(for constant rotative speed of the capstan array) torque on the torquewrap-around capstan 226. The strand B proceeding from its wrap-aroundposition on the periphery of torque wrap-around cap 204 exerts acounter-torque on cap 204, which is transmitted through torque shaft 200to the gears 272, 274 and the brake-clutch arrangement between gear 274and gear 264. The strand B will build up a suliicient wraparound angleon the periphery of torque wrap-around cap 204 to create an outputtension in strand B as it proceedsto the metering capstan 270bsufficient to counter-balance the torque transmitted to the cap 204 bythe gear and clutch-brake system 262, 264, 284, 272, 274. By varying theaxial position of shaft 266 and thus the axial spacing between gears274, 264, the effective centrifugal clutch-brake action may beselectively varied to produce a selected output tension in strand B forany particular rate of rotation of the balloon of strand A. It will beapparent, as stated above, that the centrifugal clutch-brake action ontorque wrap around capstan 226 for any particular setting of the shaft266 will be a function of the speed of rotation of the balloon of strandA, the clutch-braking action being greater at high speeds than at lowspeeds due to the increased difierential centrifugal force exerted bythe blocks 284.

Thus it will be seen that the function of this arrangement as a Whole issimilar to that of the first described embodiment in that asubstantially constant torque is maintained on torque wrap-aroundcapstan 226 for any particular rate of rotation of the balloon of strandA, with the brake torque on capstan 226 varying as a function of a rateof rotation of this balloon. It will be noted that the torque exerted oncapstan 226 through the clutch-brake system is similarly drag or braketorque in the sense of resisting the torque exerted by the strand B onthe torque wrap-around capstan 226 which latter torque may 'be viewed astending to rotate the capstan 226 relative to rotor shaft 256,irrespective of whether the gear ratios are so arranged that the torquecapstan tends to lead or lag the rotor shaft. This system is, therefore,also highly advantageous when used in conjunction with a wrap-aroundstep tension balloon shape control such as that illustrated at 17 inFIGURE 1. However, it will 'be apparent that one obvious disadvantage ofthis system is the use of a mechanical gearing and frictional clutcharrangement for the purpose of obtaining a desired brake torque on thetorque wraparound capstan, whereas the preceding described arrangementrequires only a simple magnetic brake for this puipose. On the otherhand, this second embodiment is in some ways more advantageous than thepreceding embodiment in that there is less power consumed and lessheating of the parts in the braking assembly.

In another modification as disclosed in FIGURE 9, there is also employeda friction clutch-brake arrangement which efiectively reduces the powerrequired to maintain the desired brake torque on the torque shaft 300 ofthe torque wrap-around capstan. In this embodiment, the torque impartedto the torque shaft 3% by the friction clutch 'brake arrangement will besubstantially constant for all operating speeds of the balloon strand Aand of torque shaft 300.

In this embodiment, the rotor shaft end nut 358 has gear teeth formed onthe periphery of the lower end thereof which engage with an idler gear362 of a differential idler gear system 360 rotatably mounted on a shaft370 which is suitably supported eccentrically of the axis of the torqueshaft 300. Idler gear system 369 has a second gear 364 fixedly connectedto or formed integral with gear 362; the differential ratio between thegears 362 and 364 or the idler gear system 360 being small (e.g. of theorder of that provided by one or two teeth difference, or more ifdesired). Gear 364 meshes with gear 366 which is loosely mounted on thetorque shaft 390 for rotation thereon. Torque shaft 300 has fixedlysecured thereto in any suitable manner a friction disc 368 beneath thelower end of nut-gear 358 and in face-to-face relation with gear 366.Gear 366 is adjustably held in thrust engagement with the friction disc368 through the medium of a thrust spring 372, thrust bearing 373, andthrust nut 374, the latter of which is threadedly mounted on the lowerend of torque shaft 300. By axially adjusting the thrust nut 374 thethrust exerted by gear 366 on friction disc 368 may be varied as desiredto effect the desired torque transmission between gear 366 an disc 368.This will effectively determine the brake torque exerted on torque shaft300 for any rotative speed of rotor shaft 356, and will thereby yield asubstantially constant output tension in the strand B passing throughthe bore in torque shaft 309 as it leaves the wrap-around cap (notshown) connected thereto.

Due to the extremely fine degree of tension control which may beobtained on the strands A and B with the combination system according tothis invention, particularly the system employing a similar dynamictension control for both the inner and outer strands, it may be desiredin some instances .to simplify the plying apparatus by elimination ofthe metering capstans, although for most practical purposes it will befound extremely advantageous to employ an arrangement utilizing suchmetering capstans. In FIGURE 10, there is shown schematically asimplified arrangement wherein a pair of simple pigtail guides aresubstituted for the metering capstans. 456 is rotatably mounted on asuitable support 432 through the medium of one or more low frictionbearings 448. Torque capstan 426 is suitably rotatably mounted in lowfriction bearings 494 and 498 which are press fit in spaced apartrelation in shouldered end recesses in the axial bore of rotor 456.Torque capstan 426 has an eddy current disc fixedly secured to its lowerend, a portion of which is disposed in the air gap of one or moremagnets 412. An axial bore 462 is formed in torque capstan 426 whichsuitably connects with a spiral groove 406 formed at or near the upperend of the torque capstan.

Secured in symmetrical spaced apart relation on the upper end of rotor456 are two guides 476a and 47% (which may suitably be of the pigtailtype for ease of thread-up, if desired) which serve to guide the strandsA and B, respectively, to the ply point.

The operation of this embodiment is similar to that of FIGURE 1 exceptfor the elimination of the strand metering function of the meteringcapstans, which are omitted in this embodiment. Further description ofthe operation of this embodiment is therefore not made, since such willbe apparent from the foregoing description in connection with FIGURE 1.However, it will be noted as stated above that in this embodiment theformation of a satis- In this arrangement, the axially bored rotorfactory plied cord or yarn, etc, will be substantially dependent on themaintenance of very low, if not substantially zero, differential tensionbebtween the two strands A and B as they proceed to the ply point. Thisis accomplished through the matched characteristics of the wraparoundstep tension control for the outer strand A and the speed responsivelybraked torque wray-around capstan for maintaining tension on the innerstrand B.

In FIGURES 13 and 14 there is disclosed an alternate embodiment of thetorque wrap-around cap. In this embodiment the torque metering cap 104ahas a symmetrical spiral groove 106a formed in its upper end in asubstantially S-shape. This groove 106a obviously might also be formedin a reverse S-shape, as might the groove 106 be reversed, if desired,in the event that the arrangement or rotational direction of the partsis such as to cause the wrap-around of strand B in the oppositedirection to that for which the illustrated capstans are designed. Itwill also be apparent that the groove may in some instances be radial,etc., or may take the form of a transverse port in the side of theWrap-around cap and connecting the axial bore 102 of torque shaft withthe wrap-around periphery of the wrap-around cap.

The center of groove 136a connects with the axial bore 195:: formedtherein and which is arranged for alignment with the bore 102 of thetorque shaft 100. This cap 194:: has the advantage of ease of dynamicbalance due to its symmetrical groove 106a; however, due to the bore165a being axial rather than off center as in the embodiment of FIGURES1, 10 and 11, etc., it will be apparent that this arrangement will notin itself guide the strand B through bore 105:: precisely coaxiallysince the surface of bore 16511 is necessarily displaced from the axisof cap 164a by a distance equal to the radius of the bore. It will bedesirable, however, in many cases to form the bore 105:: of slightlysmaller diameter than the bore through the torque shaft 100 in order tomore nearly center the strand, and particularly in order to guide thestrand along a line out of contact with the interior of bore 192. Itwill be seen that in operation the strand B may be guided through eitherpath of the double spiral groove 106a in the course of its passage frombore 105a to the circumferential periphery of the cap.

Referring to FIGURES 15 and 16, there is shown a further modificationfor increasing the eifective traction on the strand B (or both strandsif desired) as it passes over its metering capstan, and which maysuitably be employed with any of the embodiments except that of FIG- URE10. In this modification the strand metering capstan 5701) has formedthereon a pair of grooves 572k in lieu of the single groove disclosed inthe preceding embodiments in order to provide an increased angle oftractive engagement between the strand B and the metering capstan 57Gbto insure against possibility of slippage thereon. In order to providefor guidance of the strand from the peripheral surface of cap 594 to thefirst groove 57217 and to provide for intra groove transfer of thestrand B between the two grooves 57% the strand guide finger plate 575is fixedly mounted on the head upper end of rotor shaft 556, as throughan Allen cap screw 576.

The finger plate 575 has an intermediate wide smooth strand guidingsurface 577 formed thereon which serves to guide the strand as itproceeds from the periphery of cap 584 to the first or inner groove5721;. The strand guiding surface 577 tapers to a terminal yarn engagingfinger 578 which lies above and between the two grooves 57%, and servesto guide the strand in intra groove cross-over after the strand haspassed almost completely around the inner groove 572b and during itstransfer to the second or outer groove on the metering capstan 57Gb.After passage around the second groove the strand B then proceeds in theusual manner to the ply point.

While only mechanical and magnetic brakes have been illustrated, andsuch are preferred for various reasons as described herein, it will beapparent that other suitable brakes such as the viscous fluid type mightbe utilized if desired. For example, in FIGURE 1 a fluid or air andpaddle wheel assembly might be substituted for the magnet and discarrangement; while in FIGURE 5 a similar or other viscous fluid brakemight be substituted for the centrifugally operable mechanical frictionbrake. Also, in connection with the use of brakes of the magnetic type,electromagnetic or hybrid electromagnetic-permanent magnet types ofbrakes might be utilized, if desired, in lieu of the permanent magnettype brakes illustrated, such being particularly useful in permittingadjustment of the inner strand tension through electromagnetic braketorque control during full operation of the apparatus.

It will be understood that although the preferred and most highlyadvantageous arrangement embodying the rotatably driven torquewrap-around capstan tension device is that illustrated wherein twostrands are plied together, with one of the strands being tensioned bythis device and the other ballooned strand being employed as a powersource for actuating the device, this aspect per se of the inventionreadily lends itself to other embodiments and uses, both separately andin other combinations.

It will be further understood that relative terminology, such as above,below, lower, upper, inverted, etc., is used in the specification and/orclaims solely for describing the relationship of certain elements withre spect to other elements when the apparatus is in its normal uprightposition and should not be construed as limiting the elements of theinvention of this precise position.

While I have shown several embodiments of the various aspects of thisinvention, it will readily be apparent to one skilled in the art thatmany other embodiments and modifications are possible within the scopeand spirit of the invention. It is, therefore, to be understood that theinvention is not to be limited by the specific embodiments hereinillustrated, but only by the scope of the appended claims.

I claim:

1. Ply action apparatus for plying together two or more strands,comprising a rotatable strand guiding means for guiding each of thestrands to a ply point, first dynamic strand-tension-responsivenegative-feed-back tension control means for a first strand being plied,and second dynamic strand-tension-responsive negative-feed-back tensioncontrol means for a second strand being plied, each of said tensioncontrol means being substantially mutually independent of one anotherand being negative-feed-back responsive to the tension in itsrespectively tensioned strand to vary its tension compensating eifect onsaid respective strand in an amount inversely proportional to thetension in said respective strand.

2. Ply action apparatus according to claim 1 wherein said first tensioncontrol means has operatively associated therewith means for drivingsaid first strand in a balloon about a portion of the path of saidsecond strand.

3. Ply action apparatus according to claim 1 wherein each of saidtension control means has a substantially similar tension controlcharacteristic.

4. Ply action apparatus according to claim 3 wherein said tensioncontrol characteristic for each of said tension control means is afunction of plying rate.

5. Ply action apparatus for plying together two or more strands,comprising a rotatable strand guiding means for guiding each of thestrands to a ply point, first dynamic feed back tension control meansfor a first strand being plied, and second dynamic feed back tensioncontrol means for a second strand being plied, said second tensioncontrol means comprises a rotatable capstan, torque brake meansoperatively connected to said capstan, and means for guiding said secondstrand into sliding frictional variable wraparound engagement with saidcapstan, the wraparound angle being a function of the tension in saidsecond strand and the braking torque exerted on said capstan by saidtorque brake means.

6. Ply action apparatus according to claim 5 wherein means are providedfor driving said first strand in ballooned relation about a portion ofthe path of said second strand, said first tension control meanscomprising a wraparound step, and means for rotating said wraparoundstep.

7. Ply action apparatus according to claim 1, further comprising strandmetering means for metering each of the strands as it proceeds in itspath during plying.

8. Ply action apparatus according to claim 1 wherein one of said strandsis fed in a balloon about the other strand, each of said tension controlmeans having a tension control characteristic which is a function of therotational velocity of said balloon.

9. Ply action apparatus for plying together two or more strands,comprising a rotatable strand guiding means for guiding each of thestrands to a ply point, first dynamic feed back tension control meansfor a first strand being plied, and second dynamic feed back tensioncontrol means for a second strand being plied each of said tensioncontrol means being substantially mutually independent of one anotherand being responsive to the tension in its respectively tensioned strandto vary its tension compensating eflect on said respective strand, oneof said tension control means including a centrifugally operable brake,a rotatable strand engaging member, and a step-down drive connectionbetween said strand engaging member and said centrifugally operablebrake.

10. Ply action apparatus for plying together two or more strands,comprising a rotatable strand guiding means for guiding each of thestrands to a ply point, first dynamic feed back tension control meansfor a first strand being plied, and second dynamic feed back tensioncontrol means for a second strand being plied each of said tensioncontrol means being substantially mutually independent of one anotherand being responsive to the tension in its respectively tensioned strandto vary its tension compensating effect on said respective strand, oneof said tension control means including a magnetic brake having a discrotor and a stator, and a strand engaging member rotatable insynchronism with said rotor.

11. Ply action apparatus for plying together two or more strands,comprising a rotatable strand guiding means for guiding each of thestrands to a ply point, first dynamic feed back tension control meansfor a first strand being plied, and second dynamic feed back tensioncontrol means for a second strand being plied each of said tensioncontrol means being substantially mutually independent of one anotherand being responsive to the tension in its respectively tensioned strandto vary its tension compensating effect on said respective strand, saidsecond tension control means including a rotatable strand engagingcapstan, and including a torque brake operatively connected to saidcapstan.

12. Ply action apparatus according to claim 11 wherein said capstan hasan axial strand guiding bore therein and a transversely extending strandguiding surface formed thereon and disposed between said bore and theperiphery of said capstan.

13. A strand tension device comprising a pair of members rotatablymounted in concentric relation about a common axis, said members beingalso rotatable relative to one another about said common axis, strandguide means on one of said members resistive to torque exerted by astrand in one direction about said axis, and strand guide means on theother of said members resistive to torque exerted thereon by a strand inthe opposite direction about said axis.

14. A strand tension device comprising a pair of members rotatablymounted in concentric relation one within the other, said members beingalso rotatable relative to one another about their common axis, strandguide means on one of said members resistive to torque exerted by astrand in one direction about said axis, and strand guide means on theother of said members resistive to torque exerted thereon by a strand inthe opposite direction about said axis.

15. A strand tension device according to claim 14, the inner of saidconcentric members having an axial strand guiding hole therein.

16. A strand tension device according to claim 15, wherein one of saidguide means includes a transverse slot at one end of said inner member.

17. A strand tension device according to claim 16 wherein said slot hasa spiral configuration.

18. A strand tension device according to claim 14 wherein the inner ofsaid concentric members extends axially beyond the outer of saidmembers, said inner member having an axial strand guiding hole formedtherein and extending therethrough at least partially in an axialdirection.

19. A strand tension device according to claim 18 wherein the extendedend of said inner member forms a cylindrical yarn engaging step, saidguide means on the outer of said members having a strand guiding surfacedisposed axially inwardly from the end of said cylindrical step so as tocause a strand fed from the extended end and about said guide means onsaid inner member to tend to be wrapped about said step upon relativerotation of said members.

20. A strand tension device according to claim 14 wherein there isprovided brake means adapted to resist rotation of one of said members.

21. A strand tension device according to claim 14 wherein there isprovided brake means operatively connected to one of said members andadapted to resist rotation thereof.

22. A strand tension device according to claim 21 wherein said brakemeans comprises a magnet coupled to the inner of said members throughmagnetic induction.

23. A strand tension device according to claim 22 wherein said brake isan eddy current magnetic brake.

24. A strand tension device according to claim 14 wherein there isprovided brake means operatively connected to the inner of said membersand adapted to resist rotation thereof, said brake means comprising afriction brake.

25. A strand tension device according to claim 24 wherein said frictionbrake forms an operative connection between said members.

26. A strand tension device according to claim 25 wherein said operativeconnection comprises a difierential gear ratio system and a frictionclutch-brake operatively connecting said members.

27. A strand tension device according to claim 14 and including acentrifugally operable brake operatively connected to one of saidmembers.

28. A strand tension device according to claim 14 wherein there isprovided brake means operatively connected to the inner of said membersand adapted to resist rotation thereof, said operative connectioncomprising a differential drive ratio system.

29. A strand tension device comprising a member rotatably mounted forcontinuous rotating movement about an axis, strand engaging means on theperipheral surface of said member, a portion of the said engagingsurface of said strand engaging means extending in a directiontransverse to said axis for guiding a strand and positively transmittinga torque from said strand to said member in a first rotative directionabout said axis, torque drag means comprising a substantially constanttorque brake adapted to impart a substantially constant drag torque tosaid member in a direction opposite to said strand-exerted torque, andmeans additional to said strand adapted to impart rotation to saidmember.

30. A strand tension device according to claim 29 wherein said constanttorque brake is selectively adjustable.

31. A strand tension device according to claim 29 wherein saidadditional means comprises guide means separate from said member andadapted to guide said strand and a second strand in rotativelyintercoupled relation about said axis.

32. A strand tension device comprising a member rotatably mounted formovement about an axis, strand engaging means on the peripheral surfaceof said member, a portion of the said engaging surface of said strandengaging means extending in a direction transverse to said axis forguiding a strand and positively transmitting a torque from said strandto said member in a first rotative direction about said axis, torquedrag means comprising a substantially constant torque brake adapted toimpart a substanially constant drag torque to said memher in a directionopposite to said strand-exerted torque, and means additional to saidstrand adapted to impart rotation to said member, said additional meanscomprises a second strand, and guide means separate from said member foreach of said strands and intercoupling the rotative movement about saidaxis of said first mentioned strand with said second strand.

33. A strand tension device according to claim 29 wherein said brake isa hysteresis magnet brake having a rotatable element and a normallystationary element, said rotatable element being rotatable insynchronism with said first mentioned member.

34. A strand tension device comprising a member rotatably mounted formovement about an axis, strand engaging means on the peripheral surfaceof said member, a portion of the said engaging surface of said strandengaging means extending in a direction transverse to said axis forguiding a strand and positively transmitting a torque from said strandto said member in a first rotative direction about said axis, torquedrag means comprising a substantially constant torque brake adapted toimpart a substantially constant drag torque to said member in adirection opposite to said strand-exerted torque, and means additionalto said strand adapted to impart rotation to said member, said magneticbrake comprises two relatively movable component members including amagnet and a metallic disc member concentric with said axis, one of saidcomponent members of said brake being mounted for rotation with saidfirst mentioned member.

35. A strand tension device comprising a member having an end peripheralsurface and a radially outer peripheral surface and being mounted forrotation about an axis; rotation-resisting torque means arranged foroperative connection to said member to apply a rotation resisting torqueto said member; a substantially axially disposed strand guide; saidmember having a strand engaging means having a strand engaging torquetransmitting surface transverse to said axis and operatively connectedthrough said member to said rotation-resisting torque means, for guidinga strand between said axially disposed guide and the radially outerperipheral surface of said member; and strand guide means disposed inspaced-apart relation to said member and transversely spaced from saidaxis, said last named strand guide means being mounted for rotationabout said axis.

36. A strand tension device according to claim 35 wherein said lastnamed strand guide means comprises a rotatable capstan, and supportmeans for said capstan, said support means being rotatable about saidaxis.

37. A strand tension device according to claim 36 wherein there isfurther provided a second capstan mounted on said support means forguiding a second strand, said capstans being adapted to rotate insynchronous relation about secondary axes separate from said firstmentioned axis.

38. A strand tension device according to claim 37 wherein one of saidcapstans has a double annular groove formed thereon, and intra-grooveguide means separate from said one capstan for guiding a strand from oneto the other of said grooves.

39. A strand tension device according to claim 35 wherein said memberhas an axially extending hole formed therein, the bounding surfa.-e ofsaid hole forming said axially disposed guide.

40. Ply action apparatus for plying together two or more strands,comprising a rotatable strand guiding means for guiding each of thestrands to 2. ply point, first dynamic feed back tension control meansfor a first strand being plied, and second dynamic feed back tensioncontrol means for a second strand being plied each of said tensioncontrol means being substantially mutually independent of one anotherand being responsive to the tension in its respectively tensioned strandto vary its tension compensating efifect on said respective strand, oneof said tension control means including a centrifugal brake having arotor and a stator, and a strand engaging member rotatable insynchronism with said rotor.

41. Ply action apparatus according to claim 40 further comprising astep-down drive connection between said strand engaging member and saidrotor.

42. Ply action apparatus for plying together two or more strands,comprising a rotatable strand guiding means for guiding each of thestrands to a ply point, first dynamic feed back tension control meansfor a first strand being plied, and second dynamic feed back tensioncontrol means for a second strand being plied each of said tensioncontrol means being substantially mutually independent of one anotherand being responsive to the tension in its respectively tensioned strandto vary its tension compensating effect on said respective strand, one

18 of said tension control means including a magnetic brake having arotor and a stator, and a strand engaging member rotatable insynchronisrn with said rotor.

43. Ply action apparatus for plying together two or more strands,comprising a rotatable strand guiding means for guiding each of thestrands to a ply point, first dynamic feed back tension control meansfor a first strand being plied, and second dynamic feed back tensioncontrol means for a second strand being plied each of said tensioncontrol means being substantially mutually independent of one anotherand being responsive to the tension in its respectively tensioned strandto vary its tension compensating effect on said respective strand, oneof said tension control means including a brake having a rotor and astator, and a strand engaging member rotatable in synchronous with saidrotor.

44. Ply action apparatus according to claim 43 further comprising astep-down drive connection between said strand engaging member and saidrotor.

References Cited in the file of this patent UNITED STATES PATENTS2,689,449 Clarkson Sept. 21, 1954 2,732,680 Vibber Jan. 31, 1956 2,76,160 Vibber Feb. 28, 1956 2,753,679 Von Schmoller et a1. July 10, 19562,869,313 Vibber Jan. 20, 1959 FOREIGN PATENTS 523,245 Belgium Oct. 31,1953

